WellNuo/hooks/__tests__/useDebounce.test.ts

import { renderHook, act } from '@testing-library/react-native';
import { useDebounce } from '../useDebounce';

jest.useFakeTimers();

describe('useDebounce', () => {
  beforeEach(() => {
    jest.clearAllTimers();
  });

  describe('leading edge (default)', () => {
    it('should execute callback immediately on first call', () => {
      const callback = jest.fn();
      const { result } = renderHook(() => useDebounce(callback, { delay: 1000 }));

      act(() => {
        result.current.debouncedFn();
      });

      expect(callback).toHaveBeenCalledTimes(1);
    });

    it('should ignore subsequent calls within delay period', () => {
      const callback = jest.fn();
      const { result } = renderHook(() => useDebounce(callback, { delay: 1000 }));

      // First call - executes immediately
      act(() => {
        result.current.debouncedFn();
      });
      expect(callback).toHaveBeenCalledTimes(1);

      // Second call within delay - ignored
      act(() => {
        jest.advanceTimersByTime(500);
        result.current.debouncedFn();
      });
      expect(callback).toHaveBeenCalledTimes(1);

      // Third call within delay - ignored
      act(() => {
        jest.advanceTimersByTime(400);
        result.current.debouncedFn();
      });
      expect(callback).toHaveBeenCalledTimes(1);
    });

    it('should allow execution after delay period has passed', () => {
      const callback = jest.fn();
      const { result } = renderHook(() => useDebounce(callback, { delay: 1000 }));

      // First call
      act(() => {
        result.current.debouncedFn();
      });
      expect(callback).toHaveBeenCalledTimes(1);

      // Wait for delay to pass
      act(() => {
        jest.advanceTimersByTime(1000);
      });

      // Second call after delay - executes
      act(() => {
        result.current.debouncedFn();
      });
      expect(callback).toHaveBeenCalledTimes(2);
    });

    it('should pass arguments to callback', () => {
      const callback = jest.fn();
      const { result } = renderHook(() => useDebounce(callback, { delay: 1000 }));

      act(() => {
        result.current.debouncedFn('test', 123, { key: 'value' });
      });

      expect(callback).toHaveBeenCalledWith('test', 123, { key: 'value' });
    });
  });

  describe('trailing edge', () => {
    it('should delay execution on trailing edge', () => {
      const callback = jest.fn();
      const { result } = renderHook(() => useDebounce(callback, { delay: 1000, leading: false }));

      act(() => {
        result.current.debouncedFn();
      });

      // Should not execute immediately
      expect(callback).not.toHaveBeenCalled();

      // Should execute after delay
      act(() => {
        jest.advanceTimersByTime(1000);
      });
      expect(callback).toHaveBeenCalledTimes(1);
    });

    it('should reset timer on subsequent calls', () => {
      const callback = jest.fn();
      const { result } = renderHook(() => useDebounce(callback, { delay: 1000, leading: false }));

      // First call
      act(() => {
        result.current.debouncedFn();
      });

      // Second call before timer fires - resets timer
      act(() => {
        jest.advanceTimersByTime(500);
        result.current.debouncedFn();
      });

      // Advance to original timeout - should not fire
      act(() => {
        jest.advanceTimersByTime(500);
      });
      expect(callback).not.toHaveBeenCalled();

      // Advance to new timeout - should fire once
      act(() => {
        jest.advanceTimersByTime(500);
      });
      expect(callback).toHaveBeenCalledTimes(1);
    });
  });

  describe('isDebouncing', () => {
    it('should return true within delay period', () => {
      const callback = jest.fn();
      const { result } = renderHook(() => useDebounce(callback, { delay: 1000 }));

      act(() => {
        result.current.debouncedFn();
      });

      expect(result.current.isDebouncing()).toBe(true);

      act(() => {
        jest.advanceTimersByTime(500);
      });
      expect(result.current.isDebouncing()).toBe(true);
    });

    it('should return false after delay period', () => {
      const callback = jest.fn();
      const { result } = renderHook(() => useDebounce(callback, { delay: 1000 }));

      act(() => {
        result.current.debouncedFn();
      });

      act(() => {
        jest.advanceTimersByTime(1000);
      });

      expect(result.current.isDebouncing()).toBe(false);
    });
  });

  describe('cancel', () => {
    it('should cancel pending trailing edge execution', () => {
      const callback = jest.fn();
      const { result } = renderHook(() => useDebounce(callback, { delay: 1000, leading: false }));

      act(() => {
        result.current.debouncedFn();
      });

      // Cancel before timer fires
      act(() => {
        jest.advanceTimersByTime(500);
        result.current.cancel();
      });

      // Advance past original timeout
      act(() => {
        jest.advanceTimersByTime(600);
      });

      expect(callback).not.toHaveBeenCalled();
    });
  });

  describe('custom delay', () => {
    it('should respect custom delay value', () => {
      const callback = jest.fn();
      const { result } = renderHook(() => useDebounce(callback, { delay: 2000 }));

      act(() => {
        result.current.debouncedFn();
      });
      expect(callback).toHaveBeenCalledTimes(1);

      // Call within 2 seconds - ignored
      act(() => {
        jest.advanceTimersByTime(1500);
        result.current.debouncedFn();
      });
      expect(callback).toHaveBeenCalledTimes(1);

      // Call after 2 seconds - executes
      act(() => {
        jest.advanceTimersByTime(500);
        result.current.debouncedFn();
      });
      expect(callback).toHaveBeenCalledTimes(2);
    });
  });

  describe('rapid clicks simulation', () => {
    it('should handle rapid refresh button clicks correctly', () => {
      const callback = jest.fn();
      const { result } = renderHook(() => useDebounce(callback, { delay: 1000 }));

      // Simulate 5 rapid clicks within 2 seconds
      act(() => {
        result.current.debouncedFn(); // Click 1 - executes
        jest.advanceTimersByTime(200);
        result.current.debouncedFn(); // Click 2 - ignored
        jest.advanceTimersByTime(300);
        result.current.debouncedFn(); // Click 3 - ignored
        jest.advanceTimersByTime(400);
        result.current.debouncedFn(); // Click 4 - ignored
        jest.advanceTimersByTime(400);
        result.current.debouncedFn(); // Click 5 - executes (>1000ms since last execution)
      });

      // Only first and last should execute
      expect(callback).toHaveBeenCalledTimes(2);
    });
  });
});